Devices method and computer program for position determination

1. A device for position determination, comprising a processing means for determining a position on a surface, on the basis of an image of a position-coding pattern on the surface, wherein the processing means is arranged to decide whether it is possible to determine an acceptable position on the surface on the basis of the position-coding pattern in the image, and to cause a first writing means to write on the surface depending upon the result of said decision.

2. The device as claimed in claim 1 , wherein the position-coding pattern contains elements each of which has at least two possible decoding values, the processing means being arranged to identify in the image a plurality of said elements, and, for each identified element, to calculate for each possible decoding value an associated value probability that the element has this decoding value.

3. The device as claimed in claim 2 , wherein the processing means is arranged to identify elements, each of which comprises at least one mark, the value probabilities being calculated on the basis of the size of the marks in relation to a number of ideal sizes.

4. The device as claimed in claim 2 , wherein the processing means is arranged to identify elements, each of which comprises at least one mark which is associated with one reference point from among a number of reference points in a reference system, and wherein the value probabilities are calculated on the basis of the location of the marks in relation to the reference points with which they are associated.

5. The device as claimed in claim 4 , wherein the reference system is a raster and the reference points are raster points, each of which consists of an intersection in the raster.

6. The device as claimed in claim 1 wherein the processing means is arranged to cause the first writing means to write on the surface only if the processing means decides that it is possible to determine the acceptable position.

7. The device as claimed in claim 1 , wherein the processing means is arranged to determine a measure for how much information the image contains concerning a position on the surface.

8. The device as claimed in claim 7 , wherein the processing means is arranged to determine said measure on the basis of contrast distributions between light and dark areas in the image.

9. The device as claimed in claim 7 , wherein the processing means is arranged to determine said measure on the basis of the number of separate objects that are identifiable in the image.

10. The device as claimed in claim 7 , wherein the position-coding pattern contains elements each of which has at least two possible decoding values, the processing means being arranged to identity in the image a plurality of said elements, and, for each identified element, to calculate for each possible decoding value an associated value probability that the element has this decoding value, and

wherein the processing means is arranged to determine said measure on the basis of the value probabilities for the identified elements.

11. The device as claimed in claim 7 , wherein the processing means is arranged to compare said measure with a predetermined limit measure, it being possible to determine a position on the surface if said measure exceeds said limit measure.

12. The device as claimed in claim 1 , wherein the processing means is arranged to decide that it is possible to determine the acceptable position it it is possible to determine a position on the basis of the position-coding pattern in the image.

13. The device as claimed in claim 1 , wherein the processing means is arranged, in the case when it is possible to determine a position on the basis of the position-coding pattern in the image, to determine a position probability corresponding to a level of certainty with which it is possible to determine said position.

14. The device as claimed in claim 13 , wherein the position-coding pattern contains elements each of which has at least two possible decoding values, the processing means being arranged to identify in the image a plurality of said elements, and, for each identified element, to calculate for each possible decoding value an associated value probability that the element has this decoding value, and

wherein the processing means is arranged to calculate the position probability on the basis of the value probabilities for a predetermined number of the identified elements.

15. The device as claimed in claim 14 , wherein the processing means is arranged to calculate the position probability on the basis of the largest value probability for each of said predetermined number of the identified elements.

16. The device as claimed in claim 13 , wherein the processing means is arranged to decide that it is possible to determine the acceptable position if the position probability exceeds a predetermined limit value.

17. The device as claimed in claim 13 , wherein the processing means is arranged to decide that it is possible to determine the acceptable position if the position probability exceeds a predetermined limit value, and said position has a permitted location in relation to a previously determined acceptable position.

18. The device as claimed in claim 13 , wherein the processing means is arranged to decide that it is possible to determine the acceptable position if the position probability exceeds a predetermined limit value, and said position lies within a predetermined distance from a previously determined acceptable position.

19. The device as claimed in claim 1 , wherein the processing means is arranged to decide that it is possible to determine the acceptable position if it is possible to determine a position on the basis of the position-coding pattern in the image, and said position has a permitted location in relation to a previously determined acceptable position.

20. The device as claimed in claim 1 , wherein the processing means is arranged to decide that it is possible to determine the acceptable position if it is possible to determine a position on the basis of the position-coding pattern in the image, and said position lies within a predetermined distance from a previously determined acceptable position.

21. The device for position determination as claimed in claim 1 , further comprising the first writing means.

22. The device as claimed in claim 21 , wherein the first writing means is a nozzle that is arranged to dispense ink onto the surface.

23. The device as claimed in claim 21 , further comprising a second writing means for writing on the surface irrespective of whether it is possible to determine the acceptable position on the surface on the basis of the image.

24. The device as claimed in claim 23 or 24 , wherein the second writing means is a nozzle that is arranged to dispense ink onto the surface.

25. The device as claimed in claim 21 , further comprising a second writing means for writing on the surface when the first writing means is not writing on the surface.

26. The device as claimed in claim 1 , further comprising a sensor for recording said image of the position-coding pattern.

27. The device as claimed in claim 1 , further comprising a transceiver for wireless transmission of data from the device to an external unit.

28. The device as claimed in claim 1 , wherein the device is hand-held.

29. The device as claimed in claim 1 , wherein the device is an application-specific integrated circuit.

30. A method for position determination, comprising processing an image of a position-coding pattern on a surface, wherein the processing comprises deciding whether it is possible to determine an acceptable position on the surface on the basis of the position-coding pattern in the image, and writing on the surface depending upon the result of said decision.

31. The method as claimed in claim 30 , further comprising writing on the surface only if it is decided that it is possible to determine the acceptable position.

32. The method as claimed in claim 30 , further comprising writing on the surface by dispensing ink.

33. The method as claimed in claim 30 , further comprising recording said image of the position-coding pattern.

34. The method as claimed in claim 30 , further comprising determining a measure of how much information the image contains concerning a position on the surface, comparing said measure with a predetermined limit measure, and determining a position on the surface if said measure exceeds said limit measure.

35. The method as claimed in claim 30 , further comprising, in the case when it is possible to determine a position on the basis of the position-coding pattern in the image, determining a position probability corresponding to a level of certainty with which it is possible to determine said position, and deciding that it is possible to determine the acceptable position if the position probability exceeds a predetermined limit value.

36. The method as claimed in claim 30 , further comprising deciding that it is possible to determine the acceptable position if it is possible to determine a position on the basis of the position-coding pattern in the image, and said position has a permitted location in relation to a previously determined acceptable position.

37. A computer readable medium containing instructions, executed by a processor, for performing a method for position determination comprising:

processing an image of a position-coding pattern on a surface, wherein the processing comprises deciding whether it is possible to determine an acceptable position on the surface on the basis of the position-coding pattern in the image, and

writing on the surface depending upon the result of the decision.

38. The computer readable medium of claim 37 , further comprising writing on a surface by dispensing ink.

39. The computer readable medium of claim 37 , further comprising recording the image of the position-coding pattern.

40. The computer readable medium of claim 37 , further comprising determining a measure of how much information the image contains concerning a position on the surface, comparing the measure with a predetermined limit measure, and determining a position on the surface if the measure exceeds the limit measure.

41. The computer readable medium as set forth in claim 37 , further comprising in the case when it is possible to determine a position on the basis of the position-coding pattern in the image, determining a position probability corresponding to the level of certainty with which it is possible to determine the position, and deciding that it is possible to determine the acceptable position if the position probability exceeds a predetermined limit value.

42. The computer readable medium of claim 37 , further comprising deciding that it is possible to determine the acceptable position if it is possible to determine a position on the basis of the position-coding pattern in the image, and the position has a permitted location in relation to a previously-determined acceptable position.